If someone recites Al Fatiha in a relaxed manner (which sometimes changes the meaning), out of ignorance and being a non arab, thinking there is ease in the matter and it's not a sin, is his prayer valid? Many ppl I know are very lax & make mistakes bcz of this so I worry about praying behind them

Ustadh AbdulAziz al-Haqqan

It could be that you are digging too deep, and if this is waswas, cast it away may Allah reward you.